The present invention relates generally to a method for preparing cheeses, preferably natural cheeses, containing significant levels of soy protein. The process uses enzymes (preferably proteinase) to treat the soy ingredients and to form soy protein hydrolyzates. The enzyme-treated soy ingredients are complexable with casein micelles. After a heat treatment step to deactivate the enzymes, the soy protein hydrolyzate is added to a milk substrate which is then clotted, preferably using conventional rennet in combination with direct acidification or lactic acid-producing cultures, to form curds and whey. After separating the curds and whey, the curd is converted to cheese using conventional cheese-making procedures. Without the initial enzyme treatment, the intact soy ingredients would interfere with milk clotting, thereby preventing the formation of a normal cheese curd. Additionally, without the initial enzyme treatment, a significant portion of the intact soy ingredients would be lost with the whey. The partially hydrolyzated soy protein used in the present invention does not significantly interfere with milk clotting mechanisms. The partially hydrolyzated soy protein used in the present invention also tends to complex with casein, thereby leading to improved soy protein retention in the curd. Cheeses containing up to about 30 percent soy ingredients can be obtained.
Natural cheese is generally made by developing acidity in milk and setting the milk with a clotting agent, such as rennet, or by developing acidity to the isoelectric point of the protein. The set milk is cut or stirred, preferably with heating, and whey is separated from the resulting curd. The curd may be pressed to provide a cheese block. Curing typically takes place over a lengthy period of time under controlled conditions.
The health benefits of soybeans have been known for some time. Along with a tendency to lower cholesterol levels, soybeans have recently been linked with, or suggested as having, a possible role in inhibiting cancerous or tumor cells. Thus, efforts have been made to incorporate soy into a wide variety of foods. There have been many efforts to produce soy-containing cheeses prepared both with and without milk product ingredients. It has generally been difficult to incorporate significant levels of soy protein in dairy-based cheese products. For example, U.S. Pat. No. Re. 28,810 (May 11, 1976) provides a soy cheese prepared without milk solids using an aldonic acid lactone or an uronic acid lactone coagulant. Flavor producing proteolytic enzyme (i.e., proteases) could be incorporated into the product before formation of the emulsion, to the emulsion prior to fermentation, or to the cooked curd. The resulting soy cheese is reported to have texture and body similar to natural cheeses.
U.S. Pat. No. 3,982,025 (Sep. 12, 1976) provides a soy cheese spread which is prepared by mixing a soy cheese with an edible oil or fat, a cheese emulsifying melting salt, and water at elevated temperatures to liquify and homogeneously emulsify the ingredients. The soy cheese is prepared by fermenting soy milk with a lactic acid-forming cheese starter culture. The soy cheese may also be treated with a proteolytic enzyme to accelerate the enzymatic degradation of soy globulin; the proteolytic enzyme may be added before fermentation or after cooking of the soy cheese curd. U.S. Pat. No. 4,080,477 (Mar. 21, 1978) provides a process cheese-like product containing soy cheese by mixing under high shear (1) casein-containing substances derived from animal milk, (2) a cheese emulsifying salt, and (3) soy cheese. The casein-containing substances include caseinates, dairy cheese, dairy cheese curd, whole milk solids, skim milk solids, and mixtures thereof.
U.S. Pat. No. 4,284,656 (Aug. 18, 1981) provides a process for producing a high protein, low-fat foodstuff by water extraction of protein from a defatted soy bean followed by coagulation of the protein to form curds and whey, and separation and washing of the curd product. The curd product can be mixed with or incorporated into cheese. U.S. Pat. No. 4,303,691 (Dec. 1, 1981) provides a proteinaceous food product (stimulated cheese) by blending (1) a soy protein selected from the group consisting of soy isolate, cold insoluble soy fraction, or mixtures thereof, (2) gelatin, (3) hydrocolloid gum, (4) fat, and (5) water.
U.S. Pat. No. 4,349,576 (Sep. 14, 1982) and U.S. Pat. No. 4,345,438 (Mar. 6, 1984) provide vegetable protein isolates, including soy protein isolates, which can be incorporated into imitation cheese products. The vegetable isolates are reported to be prepared under conditions which precondition the proteins so that they may be converted, upon heat treatment, into protein aggregates which simulate the hydrocolloidal attributes of caseinate. More specifically, soy isolates are reported to be utilized to replace about 20 to 60 percent of the caseinate in an imitation cheese product without adversely affecting melt properties. The soy isolates are reported to be free of soy protein hydrolyzates.
U.S. Pat. No. 4,556,569 (Dec. 3, 1985) provides a cheese analog product using vegetable protein (e.g., soy protein). The product is made form soy milk, vegetable oil, dairy whey, caseinate, and water. U.S. Pat. No. 5,858,449 (Jan. 12, 1999) provides a isoflavone-enriched soy protein product which can be used as an ingredient in cheese products (as well as other food products).
Although theses methods generally provide cheese type products, it is still desirable to provide cheeses, especially natural cheese, containing soy protein which more closely mimic cheese prepared from dairy products. The present invention provides organoleptically pleasing cheese products, including natural cheeses, having significant levels of soy protein.
The present invention relates generally to a method for preparing cheeses, preferably natural cheeses, containing significant levels of soy protein. The process uses enzymes (preferably proteinase) to treat the soy ingredients and to form soy protein hydrolyzates. The enzyme-treated soy ingredients are complexable with casein micelles. After a heat treatment step to deactivate the enzymes, the soy protein hydrolyzate is added to a milk substrate which is then clotted, preferably using conventional rennet in combination with direct acidification or lactic acid-producing cultures, to form curds and whey. After separating the curds and whey, the curd is converted to cheese using conventional cheese-making procedures. Without the initial enzyme treatment, the intact soy ingredients would interfere with milk clotting, thereby preventing the formation of a normal cheese curd. Additionally, without the initial enzyme treatment, a significant portion of the intact soy ingredients would be lost with the whey. The partially hydrolyzated soy protein used in the present invention does not significantly interfere with milk clotting mechanisms. The partially hydrolyzated soy protein used in the present invention also tends to complex with casein, thereby leading to improved soy protein retention in the curd. Cheeses containing up to about 30 percent soy ingredients can be obtained.
The present invention provides a method for preparing a cheese containing soy proteins, said method comprising: (1) mixing soy flour with water to make a soy paste; (2) treating the soy paste with a proteolytic enzyme to form a hydrolyzed soy ingredient; (3) heating the hydrolyzed soy ingredient to a temperature sufficient to deactivate the proteolytic enzyme; (4) forming a milk substrate comprising milk and the deactivated, hydrolyzed soy ingredient; (5) treating the milk substrate to form curds and whey; (6) separating the curds from the whey; and (7) treating the curds to produce the cheese containing soy proteins. Preferably the milk substrate has a pH of about 4.0 to about 6.8 and is treated with a coagulating agent to form the curds and whey. Suitable coagulating agents include, but are not limited to, rennet, chymosin from non-animal sources, and other milk-clotting proteases.
The present invention also provides a method for preparing a cheese containing soy protein, said method comprising: (1) mixing hydrolyzed soy protein with milk to form a milk substrate; and (2) treating the milk substrate at a temperature and for a time sufficient to produce the cheese containing soy protein. Preferably the milk substrate also contains an acidifying agent and/or a clotting agent.
The present invention also provides cheese, including natural cheese, containing up to about 30 percent soy proteins, wherein the cheese is prepared by a method comprising: (1) mixing soy flour with water to make a soy paste; (2) treating the soy paste with a proteolytic enzyme to form a hydrolyzed soy ingredient; (3) heating the hydrolyzed soy ingredient to a temperature sufficient to deactivate the proteolytic enzyme; (4) forming a milk substrate comprising milk and the deactivated, hydrolyzed soy ingredient; (5) treating the milk substrate to form curds and whey; (6) separating the curds from the whey; and (7) treating the curds to produce the cheese containing soy proteins. Preferably the milk substrate has a pH of about 4.0 to about 6.8 and is treated with a coagulating agent to form the curds and whey. Suitable coagulating agents include, but are not limited to, rennet, chymosin from non-animal sources, and other milk-clotting proteases.
The present invention also provides cheese, including natural cheese, containing up to about 30 percent soy proteins, wherein the cheese is prepared by a method comprising: (1) mixing hydrolyzed soy protein with milk to form a milk substrate; and (2) treating the milk substrate at a temperature and for a time sufficient to produce the cheese containing soy protein. Preferably the milk substrate also contains an acidifying agent and/or a clotting agent. Preferably the soy-protein containing cheeses of this invention are natural cheeses which contain about 3 to about 30 percent soy protein.